discards on cable interface on uBR7246VXR

Unanswered Question
Mar 26th, 2009

Hi,

I have multiple uBR7246VXR and uBR10000 CMMTs.

If I compare show interfaces cable x/y and show interfaces cable x/y downstream I can see that there are output drops and discards on uBR7246VXR while on uBR10000 there are none?

How is so that identically configured interfaces with similar traffic patterns on one type of device have discards and dont have on another type of device?

**********************ON uBR7246VXR

------------------ show interface Cable5/0 downstream ------------------

Cable5/0: Downstream is up, IF output is up

2795513120 packets output, 3881130640 bytes, 24085848 discarded

0 output errors

1386 total active devices, 560 active modems

Total downstream bandwidth: 55616 Kbps

Total downstream reserved/reservable bandwidth: 1220/44492 Kbps

Estimated usable bandwidth: 50000 Kbps

Worst case latency for low latency queue: 0 usecs

Current Upper limit for worst case latency: 0 usecs

Ranging lists counts

Maintenance list 560, max 573

Continuous list 0, max 23

Pending list 0, max 4

------------------ show interface Cable5/0 ------------------

Cable5/0 is up, line protocol is up

Hardware is UBR7200 CLC, address is 0014.f1e1.288c (bia 0014.f1e1.288c)

MTU 1500 bytes, BW 50000 Kbit, DLY 1000 usec,

reliability 255/255, txload 126/255, rxload 39/255

Encapsulation MCNS, loopback not set

Keepalive set (10 sec)

ARP type: ARPA, ARP Timeout 04:00:00

Last input 00:01:13, output 00:00:00, output hang never

Last clearing of "show interface" counters never

Input queue: 0/75/81968/0 (size/max/drops/flushes); Total output drops: 63940767

Queueing strategy: fifo

Output queue: 0/40 (size/max)

30 second input rate 7815000 bits/sec, 3175 packets/sec

30 second output rate 24870000 bits/sec, 3881 packets/sec

1654211126 packets input, 3990133477 bytes, 10401965 no buffer

Received 104151143 broadcasts, 0 runts, 0 giants, 0 throttles

10853730 input errors, 8911838 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

3815858662 packets output, 3833475349 bytes, 0 underruns

0 output errors, 0 collisions, 1 interface resets

0 output buffer failures, 0 output buffers swapped out

**********************ON uBR10k

------------------ show interface Cable6/0/0 ------------------

Cable6/0/0 is up, line protocol is up

Hardware is UBR10000 CLC, address is 0021.d8d1.b248 (bia 0021.d8d1.b248)

MTU 1500 bytes, BW 50000 Kbit, DLY 1000 usec,

reliability 255/255, txload 93/255, rxload 28/255

Encapsulation MCNS, loopback not set

Keepalive set (10 sec)

ARP type: ARPA, ARP Timeout 04:00:00

Last input 00:14:38, output 00:00:00, output hang never

Last clearing of "show interface" counters never

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0

Queueing strategy: PXF First-In-First-Out

Output queue 0/64, 0 drops; input queue 0/75, 0 drops

30 second input rate 5542000 bits/sec, 2084 packets/sec

30 second output rate 18430000 bits/sec, 2588 packets/sec

4256419649 packets input, 2453722043 bytes, 3376154 no buffer

Received 26835452 broadcasts, 0 runts, 0 giants, 0 throttles

286592 input errors, 210527 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

3178709048 packets output, 1539587948 bytes, 0 underruns

0 output errors, 0 collisions, 7 interface resets

0 output buffer failures, 0 output buffers swapped out

------------------ show interface Cable6/0/0 downstream ------------------

Cable6/0/0: Downstream is up, IF output is up

2157585379 packets output, 3610803754 bytes, 0 discarded

0 output errors

914 total active devices, 366 active modems

Total downstream bandwidth: 55616 Kbps

Total downstream reserved/reservable bandwidth: 610/44492 Kbps

Estimated usable bandwidth: 50000 Kbps

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Branimir Turk Thu, 03/26/2009 - 06:16

Here are interface configurations:

*********************ON uBR7246VXR

interface Cable5/0

no ip address

load-interval 30

cable tftp-enforce

no cable packet-cache

cable bundle 2

cable downstream channel-id 122

cable downstream rate-limit token-bucket

cable downstream annex A

cable downstream modulation 256qam

cable downstream frequency 402000000

no cable downstream rf-shutdown

cable downstream rf-power 57

cable upstream max-ports 4

cable upstream 0 connector 0

cable upstream 0 frequency 58888000

cable upstream 0 ingress-noise-cancellation 200

cable upstream 0 docsis-mode tdma

cable upstream 0 channel-width 3200000 3200000

cable upstream 0 minislot-size 2

cable upstream 0 threshold snr-profiles 20 13

cable upstream 0 power-level 0

cable upstream 0 range-backoff 3 6

cable upstream 0 modulation-profile 42 41

cable upstream 0 rate-limit

no cable upstream 0 shutdown

cable upstream 1 description Divkovica SP0102

cable upstream 1 connector 1

cable upstream 1 frequency 58888000

cable upstream 1 ingress-noise-cancellation 200

cable upstream 1 docsis-mode tdma

cable upstream 1 channel-width 3200000 3200000

cable upstream 1 minislot-size 2

cable upstream 1 threshold snr-profiles 20 13

cable upstream 1 power-level 0

cable upstream 1 range-backoff 3 6

cable upstream 1 modulation-profile 42 41

no cable upstream 1 shutdown

cable upstream 2 description Bolnicka SP0401

cable upstream 2 connector 2

cable upstream 2 frequency 58888000

cable upstream 2 ingress-noise-cancellation 200

cable upstream 2 docsis-mode tdma

cable upstream 2 channel-width 3200000 3200000

cable upstream 2 minislot-size 2

cable upstream 2 threshold snr-profiles 20 13

cable upstream 2 power-level 0

cable upstream 2 range-backoff 3 6

cable upstream 2 modulation-profile 42 41

no cable upstream 2 shutdown

cable upstream 3 description Krizmanova SP0204

cable upstream 3 connector 3

cable upstream 3 frequency 58888000

cable upstream 3 ingress-noise-cancellation 200

cable upstream 3 docsis-mode tdma

cable upstream 3 channel-width 3200000 3200000

cable upstream 3 minislot-size 2

cable upstream 3 power-level 0

cable upstream 3 range-backoff 3 6

cable upstream 3 modulation-profile 41

no cable upstream 3 shutdown

pppoe enable

*********************ON uBR10k

interface Cable6/0/0

no ip address

load-interval 30

cable tftp-enforce

cable shared-secret 7

no cable packet-cache

cable bundle 3

cable downstream channel-id 140

cable downstream annex A

cable downstream modulation 256qam

cable downstream frequency 402000000

no cable downstream rf-shutdown

cable downstream rf-power 50

cable upstream max-ports 4

cable upstream 0 connector 0

cable upstream 0 frequency 58888000

cable upstream 0 docsis-mode tdma

cable upstream 0 channel-width 3200000 3200000

cable upstream 0 minislot-size 2

cable upstream 0 range-backoff 3 6

cable upstream 0 modulation-profile 21

cable upstream 0 rate-limit

no cable upstream 0 shutdown

cable upstream 1 connector 1

cable upstream 1 frequency 58888000

cable upstream 1 docsis-mode tdma

cable upstream 1 channel-width 3200000 3200000

cable upstream 1 minislot-size 2

cable upstream 1 range-backoff 3 6

cable upstream 1 modulation-profile 21

cable upstream 1 rate-limit

no cable upstream 1 shutdown

cable upstream 2 connector 2

cable upstream 2 frequency 58888000

cable upstream 2 docsis-mode tdma

cable upstream 2 channel-width 3200000 3200000

cable upstream 2 minislot-size 2

cable upstream 2 range-backoff 3 6

cable upstream 2 modulation-profile 21

cable upstream 2 rate-limit

no cable upstream 2 shutdown

cable upstream 3 connector 3

cable upstream 3 frequency 58888000

cable upstream 3 docsis-mode tdma

cable upstream 3 channel-width 3200000 3200000

cable upstream 3 minislot-size 2

cable upstream 3 range-backoff 3 6

cable upstream 3 modulation-profile 21

cable upstream 3 rate-limit

no cable upstream 3 sh

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